// Copyright (c) 2014-2019, The Monero Project
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
//    conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
//    of conditions and the following disclaimer in the documentation and/or other
//    materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
//    used to endorse or promote products derived from this software without specific
//    prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include "db_bdb.h"

#include <boost/filesystem.hpp>
#include <memory>  // std::unique_ptr
#include <cstring> // memcpy

#include "cryptonote_basic/cryptonote_format_utils.h"
#include "crypto/crypto.h"
#include "profile_tools.h"

using epee::string_tools::pod_to_hex;
#define DB_DEFAULT_TX (m_write_txn != nullptr ? *m_write_txn : (DbTxn *)nullptr)

// Increase when the DB changes in a non backward compatible way, and there
// is no automatic conversion, so that a full resync is needed.
#define VERSION 0

namespace
{

    template <typename T>
    inline void throw0(const T &e)
    {
        LOG_PRINT_L0(e.what());
        throw e;
    }

    template <typename T>
    inline void throw1(const T &e)
    {
        LOG_PRINT_L1(e.what());
        throw e;
    }

    //  cursor needs to be closed when it goes out of scope,
    //  this helps if the function using it throws
    struct bdb_cur
    {
        bdb_cur(DbTxn *txn, Db *dbi)
        {
            if (dbi->cursor(txn, &m_cur, 0))
                throw0(cryptonote::DB_ERROR("Error opening db cursor"));
            done = false;
        }

        ~bdb_cur()
        {
            close();
        }

        operator Dbc *()
        {
            return m_cur;
        }
        operator Dbc **()
        {
            return &m_cur;
        }
        Dbc *operator->()
        {
            return m_cur;
        }

        void close()
        {
            if (!done)
            {
                m_cur->close();
                done = true;
            }
        }

    private:
        Dbc *m_cur;
        bool done;
    };

    const char *const BDB_BLOCKS = "blocks";
    const char *const BDB_BLOCK_TIMESTAMPS = "block_timestamps";
    const char *const BDB_BLOCK_HEIGHTS = "block_heights";
    const char *const BDB_BLOCK_HASHES = "block_hashes";
    const char *const BDB_BLOCK_SIZES = "block_sizes";
    const char *const BDB_BLOCK_DIFFS = "block_diffs";
    const char *const BDB_BLOCK_COINS = "block_coins";

    const char *const BDB_TXS = "txs";
    const char *const BDB_TX_UNLOCKS = "tx_unlocks";
    const char *const BDB_TX_HEIGHTS = "tx_heights";
    const char *const BDB_TX_OUTPUTS = "tx_outputs";

    const char *const BDB_OUTPUT_TXS = "output_txs";
    const char *const BDB_OUTPUT_INDICES = "output_indices";
    const char *const BDB_OUTPUT_AMOUNTS = "output_amounts";
    const char *const BDB_OUTPUT_KEYS = "output_keys";

    const char *const BDB_SPENT_KEYS = "spent_keys";

    const char *const BDB_HF_STARTING_HEIGHTS = "hf_starting_heights";
    const char *const BDB_HF_VERSIONS = "hf_versions";

    const char *const BDB_PROPERTIES = "properties";

    const unsigned int MB = 1024 * 1024;
    // ND: FIXME: db keeps running out of locks when doing full syncs. Possible bug??? Set it to 5K for now.
    const unsigned int DB_MAX_LOCKS = 5000;
    const unsigned int DB_BUFFER_LENGTH = 32 * MB;
    // 256MB cache adjust as necessary using DB_CONFIG
    const unsigned int DB_DEF_CACHESIZE = 256 * MB;

#if defined(BDB_BULK_CAN_THREAD)
    const unsigned int DB_BUFFER_COUNT = tools::get_max_concurrency();
#else
    const unsigned int DB_BUFFER_COUNT = 1;
#endif

    template <typename T>
    struct Dbt_copy : public Dbt
    {
        Dbt_copy(const T &t) : t_copy(t)
        {
            init();
        }

        Dbt_copy()
        {
            init();
        }

        void init()
        {
            set_data(&t_copy);
            set_size(sizeof(T));
            set_ulen(sizeof(T));
            set_flags(DB_DBT_USERMEM);
        }

        operator T()
        {
            return t_copy;
        }

    private:
        T t_copy;
    };

    template <>
    struct Dbt_copy<cryptonote::blobdata> : public Dbt
    {
        Dbt_copy(const cryptonote::blobdata &bd) : m_data(new char[bd.size()])
        {
            memcpy(m_data.get(), bd.data(), bd.size());
            set_data(m_data.get());
            set_size(bd.size());
            set_ulen(bd.size());
            set_flags(DB_DBT_USERMEM);
        }

    private:
        std::unique_ptr<char[]> m_data;
    };

    template <>
    struct Dbt_copy<const char *> : public Dbt
    {
        Dbt_copy(const char *s) : m_data(strdup(s))
        {
            size_t len = strlen(s) + 1; // include the NUL, makes it easier for compare
            set_data(m_data.get());
            set_size(len);
            set_ulen(len);
            set_flags(DB_DBT_USERMEM);
        }

    private:
        std::unique_ptr<char[]> m_data;
    };

    struct Dbt_safe : public Dbt
    {
        Dbt_safe()
        {
            set_data(NULL);
            set_flags(DB_DBT_MALLOC);
        }
        ~Dbt_safe()
        {
            void *buf = get_data();
            if (buf != NULL)
            {
                free(buf);
            }
        }
    };

} // anonymous namespace

namespace cryptonote
{

    void BlockchainBDB::add_block(const block &blk, size_t block_weight, const difficulty_type &cumulative_difficulty, const uint64_t &coins_generated, const crypto::hash &blk_hash)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<crypto::hash> val_h(blk_hash);
        if (m_block_heights->exists(DB_DEFAULT_TX, &val_h, 0) == 0)
            throw1(BLOCK_EXISTS("Attempting to add block that's already in the db"));

        if (m_height > 0)
        {
            Dbt_copy<crypto::hash> parent_key(blk.prev_id);
            Dbt_copy<uint32_t> parent_h;
            if (m_block_heights->get(DB_DEFAULT_TX, &parent_key, &parent_h, 0))
            {
                LOG_PRINT_L3("m_height: " << m_height);
                LOG_PRINT_L3("parent_key: " << blk.prev_id);
                throw0(DB_ERROR("Failed to get top block hash to check for new block's parent"));
            }
            uint32_t parent_height = parent_h;
            if (parent_height != m_height)
                throw0(BLOCK_PARENT_DNE("Top block is not new block's parent"));
        }

        Dbt_copy<uint32_t> key(m_height + 1);

        Dbt_copy<blobdata> blob(block_to_blob(blk));
        auto res = m_blocks->put(DB_DEFAULT_TX, &key, &blob, 0);
        if (res)
            throw0(DB_ERROR("Failed to add block blob to db transaction."));

        Dbt_copy<size_t> sz(block_weight);
        if (m_block_sizes->put(DB_DEFAULT_TX, &key, &sz, 0))
            throw0(DB_ERROR("Failed to add block size to db transaction."));

        Dbt_copy<uint64_t> ts(blk.timestamp);
        if (m_block_timestamps->put(DB_DEFAULT_TX, &key, &ts, 0))
            throw0(DB_ERROR("Failed to add block timestamp to db transaction."));

        Dbt_copy<difficulty_type> diff(cumulative_difficulty);
        if (m_block_diffs->put(DB_DEFAULT_TX, &key, &diff, 0))
            throw0(DB_ERROR("Failed to add block cumulative difficulty to db transaction."));

        Dbt_copy<uint64_t> coinsgen(coins_generated);
        if (m_block_coins->put(DB_DEFAULT_TX, &key, &coinsgen, 0))
            throw0(DB_ERROR("Failed to add block total generated coins to db transaction."));

        if (m_block_heights->put(DB_DEFAULT_TX, &val_h, &key, 0))
            throw0(DB_ERROR("Failed to add block height by hash to db transaction."));

        if (m_block_hashes->put(DB_DEFAULT_TX, &key, &val_h, 0))
            throw0(DB_ERROR("Failed to add block hash to db transaction."));
    }

    void BlockchainBDB::remove_block()
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        if (m_height == 0)
            throw0(BLOCK_DNE("Attempting to remove block from an empty blockchain"));

        Dbt_copy<uint32_t> k(m_height);
        Dbt_copy<crypto::hash> h;
        if (m_block_hashes->get(DB_DEFAULT_TX, &k, &h, 0))
            throw1(BLOCK_DNE("Attempting to remove block that's not in the db"));

        if (m_blocks->del(DB_DEFAULT_TX, &k, 0))
            throw1(DB_ERROR("Failed to add removal of block to db transaction"));

        if (m_block_sizes->del(DB_DEFAULT_TX, &k, 0))
            throw1(DB_ERROR("Failed to add removal of block size to db transaction"));

        if (m_block_diffs->del(DB_DEFAULT_TX, &k, 0))
            throw1(DB_ERROR("Failed to add removal of block cumulative difficulty to db transaction"));

        if (m_block_coins->del(DB_DEFAULT_TX, &k, 0))
            throw1(DB_ERROR("Failed to add removal of block total generated coins to db transaction"));

        if (m_block_timestamps->del(DB_DEFAULT_TX, &k, 0))
            throw1(DB_ERROR("Failed to add removal of block timestamp to db transaction"));

        if (m_block_heights->del(DB_DEFAULT_TX, &h, 0))
            throw1(DB_ERROR("Failed to add removal of block height by hash to db transaction"));

        if (m_block_hashes->del(DB_DEFAULT_TX, &k, 0))
            throw1(DB_ERROR("Failed to add removal of block hash to db transaction"));
    }

    void BlockchainBDB::add_transaction_data(const crypto::hash &blk_hash, const transaction &tx, const crypto::hash &tx_hash, const crypto::hash &tx_prunable_hash)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<crypto::hash> val_h(tx_hash);

        if (m_txs->exists(DB_DEFAULT_TX, &val_h, 0) == 0)
            throw1(TX_EXISTS("Attempting to add transaction that's already in the db"));

        Dbt_copy<blobdata> blob(tx_to_blob(tx));
        if (m_txs->put(DB_DEFAULT_TX, &val_h, &blob, 0))
            throw0(DB_ERROR("Failed to add tx blob to db transaction"));

        Dbt_copy<uint64_t> height(m_height + 1);
        if (m_tx_heights->put(DB_DEFAULT_TX, &val_h, &height, 0))
            throw0(DB_ERROR("Failed to add tx block height to db transaction"));

        Dbt_copy<uint64_t> unlock_time(tx.unlock_time);
        if (m_tx_unlocks->put(DB_DEFAULT_TX, &val_h, &unlock_time, 0))
            throw0(DB_ERROR("Failed to add tx unlock time to db transaction"));
    }

    void BlockchainBDB::remove_transaction_data(const crypto::hash &tx_hash, const transaction &tx)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<crypto::hash> val_h(tx_hash);
        if (m_txs->exists(DB_DEFAULT_TX, &val_h, 0))
            throw1(TX_DNE("Attempting to remove transaction that isn't in the db"));

        if (m_txs->del(DB_DEFAULT_TX, &val_h, 0))
            throw1(DB_ERROR("Failed to add removal of tx to db transaction"));
        if (m_tx_unlocks->del(DB_DEFAULT_TX, &val_h, 0))
            throw1(DB_ERROR("Failed to add removal of tx unlock time to db transaction"));
        if (m_tx_heights->del(DB_DEFAULT_TX, &val_h, 0))
            throw1(DB_ERROR("Failed to add removal of tx block height to db transaction"));

        remove_tx_outputs(tx_hash, tx);

        auto result = m_tx_outputs->del(DB_DEFAULT_TX, &val_h, 0);
        if (result == DB_NOTFOUND)
            LOG_PRINT_L1("tx has no outputs to remove: " << tx_hash);
        else if (result)
            throw1(DB_ERROR("Failed to add removal of tx outputs to db transaction"));
    }

    void BlockchainBDB::add_output(const crypto::hash &tx_hash, const tx_out &tx_output, const uint64_t &local_index, const uint64_t unlock_time, const rct::key *commitment)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<uint32_t> k(m_num_outputs + 1);
        Dbt_copy<crypto::hash> v(tx_hash);

        if (m_output_txs->put(DB_DEFAULT_TX, &k, &v, 0))
            throw0(DB_ERROR("Failed to add output tx hash to db transaction"));
        if (m_tx_outputs->put(DB_DEFAULT_TX, &v, &k, 0))
            throw0(DB_ERROR("Failed to add tx output index to db transaction"));

        Dbt_copy<uint64_t> val_local_index(local_index);
        if (m_output_indices->put(DB_DEFAULT_TX, &k, &val_local_index, 0))
            throw0(DB_ERROR("Failed to add tx output index to db transaction"));

        Dbt_copy<uint64_t> val_amount(tx_output.amount);
        if (m_output_amounts->put(DB_DEFAULT_TX, &val_amount, &k, 0))
            throw0(DB_ERROR("Failed to add output amount to db transaction."));

        if (tx_output.target.type() == typeid(txout_sispop_tagged_key))
        {
            output_data_t od;
            od.pubkey = boost::get<txout_sispop_tagged_key>(tx_output.target).key;
            od.unlock_time = unlock_time;
            od.height = m_height;

            Dbt_copy<output_data_t> data(od);
            if (m_output_keys->put(DB_DEFAULT_TX, &k, &data, 0))
                throw0(DB_ERROR("Failed to add output pubkey to db transaction"));
        }
        else
        {
            throw0(DB_ERROR("Wrong output type: expected txout_sispop_tagged_key"));
        }

        m_num_outputs++;
    }

    void BlockchainBDB::remove_tx_outputs(const crypto::hash &tx_hash, const transaction &tx)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);

        bdb_cur cur(DB_DEFAULT_TX, m_tx_outputs);

        Dbt_copy<crypto::hash> k(tx_hash);
        Dbt_copy<uint32_t> v;

        auto result = cur->get(&k, &v, DB_SET);
        if (result == DB_NOTFOUND)
        {
            LOG_PRINT_L2("tx has no outputs, so no global output indices");
        }
        else if (result)
        {
            throw0(DB_ERROR("DB error attempting to get an output"));
        }
        else
        {
            result = cur->get(&k, &v, DB_NEXT_NODUP);
            if (result != 0 && result != DB_NOTFOUND)
                throw0(DB_ERROR("DB error attempting to get next non-duplicate tx hash"));

            if (result == 0)
                result = cur->get(&k, &v, DB_PREV);
            else if (result == DB_NOTFOUND)
                result = cur->get(&k, &v, DB_LAST);

            db_recno_t num_elems = 0;
            cur->count(&num_elems, 0);

            // remove in order: from newest to oldest
            for (uint64_t i = num_elems; i > 0; --i)
            {
                const tx_out tx_output = tx.vout[i - 1];
                remove_output(v, tx_output.amount);
                if (i > 1)
                {
                    cur->get(&k, &v, DB_PREV_DUP);
                }
            }
        }

        cur.close();
    }

    // TODO: probably remove this function
    void BlockchainBDB::remove_output(const tx_out &tx_output)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__ << " (unused version - does nothing)");
        return;
    }

    void BlockchainBDB::remove_output(const uint64_t &out_index, const uint64_t amount)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<uint32_t> k(out_index);

        auto result = m_output_indices->del(DB_DEFAULT_TX, &k, 0);
        if (result == DB_NOTFOUND)
        {
            LOG_PRINT_L0("Unexpected: global output index not found in m_output_indices");
        }
        else if (result)
        {
            throw1(DB_ERROR("Error adding removal of output tx index to db transaction"));
        }

        result = m_output_txs->del(DB_DEFAULT_TX, &k, 0);
        // if (result != 0 && result != DB_NOTFOUND)
        //    throw1(DB_ERROR("Error adding removal of output tx hash to db transaction"));
        if (result == DB_NOTFOUND)
        {
            LOG_PRINT_L0("Unexpected: global output index not found in m_output_txs");
        }
        else if (result)
        {
            throw1(DB_ERROR("Error adding removal of output tx hash to db transaction"));
        }

        result = m_output_keys->del(DB_DEFAULT_TX, &k, 0);
        if (result == DB_NOTFOUND)
        {
            LOG_PRINT_L0("Unexpected: global output index not found in m_output_keys");
        }
        else if (result)
            throw1(DB_ERROR("Error adding removal of output pubkey to db transaction"));

        remove_amount_output_index(amount, out_index);

        m_num_outputs--;
    }

    void BlockchainBDB::remove_amount_output_index(const uint64_t amount, const uint64_t global_output_index)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        bdb_cur cur(DB_DEFAULT_TX, m_output_amounts);

        Dbt_copy<uint64_t> k(amount);
        Dbt_copy<uint32_t> v;

        auto result = cur->get(&k, &v, DB_SET);
        if (result == DB_NOTFOUND)
            throw1(OUTPUT_DNE("Attempting to get an output index by amount and amount index, but amount not found"));
        else if (result)
            throw0(DB_ERROR("DB error attempting to get an output"));

        db_recno_t num_elems = 0;
        cur->count(&num_elems, 0);

        // workaround for Berkeley DB to start at end of k's duplicate list:
        // if next key exists:
        //   - move cursor to start of next key's duplicate list, then move back one
        //     duplicate element to reach the end of the original key's duplicate
        //     list.
        //
        // else if the next key doesn't exist:
        //   - that means we're already on the last key.
        //   - move cursor to last element in the db, which is the last element of
        //     the desired key's duplicate list.

        result = cur->get(&k, &v, DB_NEXT_NODUP);
        if (result != 0 && result != DB_NOTFOUND)
            throw0(DB_ERROR("DB error attempting to get next non-duplicate output amount"));

        if (result == 0)
            result = cur->get(&k, &v, DB_PREV);
        else if (result == DB_NOTFOUND)
            result = cur->get(&k, &v, DB_LAST);

        bool found_index = false;
        uint64_t amount_output_index = 0;
        uint64_t goi = 0;

        for (uint64_t i = num_elems; i > 0; --i)
        {
            goi = v;
            if (goi == global_output_index)
            {
                amount_output_index = i - 1;
                found_index = true;
                break;
            }
            if (i > 1)
                cur->get(&k, &v, DB_PREV_DUP);
        }

        if (found_index)
        {
            // found the amount output index
            // now delete it
            result = cur->del(0);
            if (result)
                throw0(DB_ERROR(std::string("Error deleting amount output index ").append(boost::lexical_cast<std::string>(amount_output_index)).c_str()));
        }
        else
        {
            // not found
            throw1(OUTPUT_DNE("Failed to find amount output index"));
        }
        cur.close();
    }

    void BlockchainBDB::add_spent_key(const crypto::key_image &k_image)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<crypto::key_image> val_key(k_image);
        if (m_spent_keys->exists(DB_DEFAULT_TX, &val_key, 0) == 0)
            throw1(KEY_IMAGE_EXISTS("Attempting to add spent key image that's already in the db"));

        Dbt_copy<char> val('\0');
        if (m_spent_keys->put(DB_DEFAULT_TX, &val_key, &val, 0))
            throw1(DB_ERROR("Error adding spent key image to db transaction."));
    }

    void BlockchainBDB::remove_spent_key(const crypto::key_image &k_image)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<crypto::key_image> k(k_image);
        auto result = m_spent_keys->del(DB_DEFAULT_TX, &k, 0);
        if (result != 0 && result != DB_NOTFOUND)
            throw1(DB_ERROR("Error adding removal of key image to db transaction"));
    }

    bool BlockchainBDB::for_all_key_images(std::function<bool(const crypto::key_image &)> f) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        bdb_cur cur(DB_DEFAULT_TX, m_spent_keys);

        Dbt_copy<crypto::key_image> k;
        Dbt_copy<char> v;
        bool ret = true;
        int result;
        while ((result = cur->get(&k, &v, DB_NEXT)) == 0)
        {
            if (!f(k))
            {
                ret = false;
                break;
            }
        }
        if (result != DB_NOTFOUND)
            ret = false;

        cur.close();
        return ret;
    }

    bool BlockchainBDB::for_all_blocks(std::function<bool(uint64_t, const crypto::hash &, const cryptonote::block &)> f) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        bdb_cur cur(DB_DEFAULT_TX, m_blocks);

        Dbt_copy<uint32_t> k;
        Dbt_safe v;
        bool ret = true;
        int result;
        while ((result = cur->get(&k, &v, DB_NEXT)) == 0)
        {
            uint64_t height = k - 1;
            blobdata bd;
            bd.assign(reinterpret_cast<char *>(v.get_data()), v.get_size());
            block b;
            if (!parse_and_validate_block_from_blob(bd, b))
                throw0(DB_ERROR("Failed to parse block from blob retrieved from the db"));
            crypto::hash hash;
            if (!get_block_hash(b, hash))
                throw0(DB_ERROR("Failed to get block hash from blob retrieved from the db"));
            if (!f(height, hash, b))
            {
                ret = false;
                break;
            }
        }
        if (result != DB_NOTFOUND)
            ret = false;

        cur.close();
        return ret;
    }

    bool BlockchainBDB::for_all_transactions(std::function<bool(const crypto::hash &, const cryptonote::transaction &)> f, bool pruned) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        bdb_cur cur(DB_DEFAULT_TX, m_txs);

        Dbt_copy<crypto::hash> k;
        Dbt_safe v;
        bool ret = true;
        int result;
        while ((result = cur->get(&k, &v, DB_NEXT)) == 0)
        {
            blobdata bd;
            bd.assign(reinterpret_cast<char *>(v.get_data()), v.get_size());
            transaction tx;
            if (!parse_and_validate_tx_from_blob(bd, tx))
                throw0(DB_ERROR("Failed to parse tx from blob retrieved from the db"));
            if (!f(k, tx))
            {
                ret = false;
                break;
            }
        }
        if (result != DB_NOTFOUND)
            ret = false;

        cur.close();
        return ret;
    }

    bool BlockchainBDB::for_all_outputs(std::function<bool(uint64_t amount, const crypto::hash &tx_hash, size_t tx_idx)> f) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        bdb_cur cur(DB_DEFAULT_TX, m_output_amounts);

        Dbt_copy<uint64_t> k;
        Dbt_copy<uint32_t> v;
        bool ret = true;
        int result;
        while ((result = cur->get(&k, &v, DB_NEXT)) == 0)
        {
            uint32_t global_index = v - 1;
            tx_out_index toi = get_output_tx_and_index_from_global(global_index);
            if (!f(k, toi.first, toi.second))
            {
                ret = false;
                break;
            }
        }
        if (result != DB_NOTFOUND)
            ret = false;

        cur.close();
        return ret;
    }

    uint64_t BlockchainBDB::get_output_global_index(const uint64_t &amount, const uint64_t &index)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        std::vector<uint64_t> offsets;
        std::vector<uint64_t> global_indices;
        offsets.push_back(index);
        get_output_global_indices(amount, offsets, global_indices);
        if (!global_indices.size())
            throw1(OUTPUT_DNE("Attempting to get an output index by amount and amount index, but amount not found"));

        return global_indices[0];
    }

    void BlockchainBDB::check_open() const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        if (!m_open)
            throw0(DB_ERROR("DB operation attempted on a not-open DB instance"));
    }

    BlockchainBDB::~BlockchainBDB()
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);

        if (m_open)
        {
            close();
        }
    }

    BlockchainBDB::BlockchainBDB(bool batch_transactions) : BlockchainDB(),
                                                            m_buffer(DB_BUFFER_COUNT, DB_BUFFER_LENGTH)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        // initialize folder to something "safe" just in case
        // someone accidentally misuses this class...
        m_folder = "thishsouldnotexistbecauseitisgibberish";
        m_run_checkpoint = 0;
        m_batch_transactions = batch_transactions;
        m_write_txn = nullptr;
        m_height = 0;

        m_hardfork = nullptr;
    }

    void BlockchainBDB::open(const std::string &filename, const int db_flags)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);

        if (m_open)
            throw0(DB_OPEN_FAILURE("Attempted to open db, but it's already open"));

        boost::filesystem::path direc(filename);
        if (boost::filesystem::exists(direc))
        {
            if (!boost::filesystem::is_directory(direc))
                throw0(DB_OPEN_FAILURE("DB needs a directory path, but a file was passed"));
        }
        else
        {
            if (!boost::filesystem::create_directories(direc))
                throw0(DB_OPEN_FAILURE(std::string("Failed to create directory ").append(filename).c_str()));
        }

        m_folder = filename;

        try
        {

            // Create BerkeleyDB environment
            m_env = new DbEnv(0); // no flags needed for DbEnv

            uint32_t db_env_open_flags = DB_CREATE | DB_INIT_MPOOL | DB_INIT_LOCK | DB_INIT_LOG | DB_INIT_TXN | DB_RECOVER | DB_THREAD;

            // Set some default values for these parameters.
            // They can be overridden using the DB_CONFIG file.
            m_env->set_cachesize(0, DB_DEF_CACHESIZE, 1);
            m_env->set_lk_max_locks(DB_MAX_LOCKS);
            m_env->set_lk_max_lockers(DB_MAX_LOCKS);
            m_env->set_lk_max_objects(DB_MAX_LOCKS);

#ifndef __OpenBSD__ // OpenBSD's DB package is too old to support this feature
            if (m_auto_remove_logs)
                m_env->log_set_config(DB_LOG_AUTO_REMOVE, 1);
#endif

            // last parameter left 0, files will be created with default rw access
            m_env->open(filename.c_str(), db_env_open_flags, 0);
            m_env->set_flags(db_flags, 1);

            // begin transaction to init dbs
            bdb_txn_safe txn;
            m_env->txn_begin(NULL, txn, 0);

            // create Dbs in the environment
            m_blocks = new Db(m_env, 0);
            m_block_heights = new Db(m_env, 0);
            m_block_hashes = new Db(m_env, 0);
            m_block_timestamps = new Db(m_env, 0);
            m_block_sizes = new Db(m_env, 0);
            m_block_diffs = new Db(m_env, 0);
            m_block_coins = new Db(m_env, 0);

            m_txs = new Db(m_env, 0);
            m_tx_unlocks = new Db(m_env, 0);
            m_tx_heights = new Db(m_env, 0);
            m_tx_outputs = new Db(m_env, 0);

            m_output_txs = new Db(m_env, 0);
            m_output_indices = new Db(m_env, 0);
            m_output_amounts = new Db(m_env, 0);
            m_output_keys = new Db(m_env, 0);

            m_spent_keys = new Db(m_env, 0);

            m_hf_starting_heights = new Db(m_env, 0);
            m_hf_versions = new Db(m_env, 0);

            m_properties = new Db(m_env, 0);

            // Tell DB about Dbs that need duplicate support
            // Note: no need to tell about sorting,
            //   as the default is insertion order, which we want
            m_tx_outputs->set_flags(DB_DUP);
            m_output_amounts->set_flags(DB_DUP);

            // Tell DB about fixed-size values.
            m_block_hashes->set_re_len(sizeof(crypto::hash));
            m_block_timestamps->set_re_len(sizeof(uint64_t));
            m_block_sizes->set_re_len(sizeof(size_t)); // should really store block size as uint64_t...
            m_block_diffs->set_re_len(sizeof(difficulty_type));
            m_block_coins->set_re_len(sizeof(uint64_t));

            m_output_txs->set_re_len(sizeof(crypto::hash));
            m_output_indices->set_re_len(sizeof(uint64_t));
            m_output_keys->set_re_len(sizeof(output_data_t));

            m_hf_starting_heights->set_re_len(sizeof(uint64_t));
            m_hf_versions->set_re_len(sizeof(uint8_t));

            // TODO: Find out if we need to do Db::set_flags(DB_RENUMBER)
            //       for the RECNO databases.  We shouldn't as we're only
            //       inserting/removing from the end, but we'll see.

            // open Dbs in the environment
            // m_tx_outputs and m_output_amounts must be DB_HASH or DB_BTREE
            //   because they need duplicate entry support.  The rest are DB_RECNO,
            //   as it seems that will be the most performant choice.
            m_blocks->open(txn, BDB_BLOCKS, NULL, DB_RECNO, DB_CREATE, 0);

            m_block_timestamps->open(txn, BDB_BLOCK_TIMESTAMPS, NULL, DB_RECNO, DB_CREATE, 0);
            m_block_heights->open(txn, BDB_BLOCK_HEIGHTS, NULL, DB_HASH, DB_CREATE, 0);
            m_block_hashes->open(txn, BDB_BLOCK_HASHES, NULL, DB_RECNO, DB_CREATE, 0);
            m_block_sizes->open(txn, BDB_BLOCK_SIZES, NULL, DB_RECNO, DB_CREATE, 0);
            m_block_diffs->open(txn, BDB_BLOCK_DIFFS, NULL, DB_RECNO, DB_CREATE, 0);
            m_block_coins->open(txn, BDB_BLOCK_COINS, NULL, DB_RECNO, DB_CREATE, 0);

            m_txs->open(txn, BDB_TXS, NULL, DB_HASH, DB_CREATE, 0);
            m_tx_unlocks->open(txn, BDB_TX_UNLOCKS, NULL, DB_HASH, DB_CREATE, 0);
            m_tx_heights->open(txn, BDB_TX_HEIGHTS, NULL, DB_HASH, DB_CREATE, 0);
            m_tx_outputs->open(txn, BDB_TX_OUTPUTS, NULL, DB_HASH, DB_CREATE, 0);

            m_output_txs->open(txn, BDB_OUTPUT_TXS, NULL, DB_RECNO, DB_CREATE, 0);
            m_output_indices->open(txn, BDB_OUTPUT_INDICES, NULL, DB_RECNO, DB_CREATE, 0);
            m_output_amounts->open(txn, BDB_OUTPUT_AMOUNTS, NULL, DB_HASH, DB_CREATE, 0);
            m_output_keys->open(txn, BDB_OUTPUT_KEYS, NULL, DB_RECNO, DB_CREATE, 0);

            m_spent_keys->open(txn, BDB_SPENT_KEYS, NULL, DB_HASH, DB_CREATE, 0);

            m_hf_starting_heights->open(txn, BDB_HF_STARTING_HEIGHTS, NULL, DB_RECNO, DB_CREATE, 0);
            m_hf_versions->open(txn, BDB_HF_VERSIONS, NULL, DB_RECNO, DB_CREATE, 0);

            m_properties->open(txn, BDB_PROPERTIES, NULL, DB_HASH, DB_CREATE, 0);

            txn.commit();

            DB_BTREE_STAT *stats;

            // DB_FAST_STAT can apparently cause an incorrect number of records
            // to be returned.  The flag should be set to 0 instead if this proves
            // to be the case.

            // ND: The bug above can occur when a block is popped and the application
            // exits without pushing a new block to the db. Set txn to NULL and DB_FAST_STAT
            // to zero (0) for reliability.
            m_blocks->stat(NULL, &stats, 0);
            m_height = stats->bt_nkeys;
            free(stats);

            // see above comment about DB_FAST_STAT
            m_output_indices->stat(NULL, &stats, 0);
            m_num_outputs = stats->bt_nkeys;
            free(stats);

            // checks for compatibility
            bool compatible = true;

            Dbt_copy<const char *> key("version");
            Dbt_copy<uint32_t> result;
            auto get_result = m_properties->get(DB_DEFAULT_TX, &key, &result, 0);
            if (get_result == 0)
            {
                if (result > VERSION)
                {
                    LOG_PRINT_RED_L0("Existing BerkeleyDB database was made by a later version. We don't know how it will change yet.");
                    compatible = false;
                }
#if VERSION > 0
                else if (result < VERSION)
                {
                    compatible = false;
                }
#endif
            }
            else
            {
                // if not found, but we're on version 0, it's fine. If the DB's empty, it's fine too.
                if (VERSION > 0 && m_height > 0)
                    compatible = false;
            }

            if (!compatible)
            {
                m_open = false;
                LOG_PRINT_RED_L0("Existing BerkeleyDB database is incompatible with this version.");
                LOG_PRINT_RED_L0("Please delete the existing database and resync.");
                return;
            }

            if (1 /* this can't be set readonly atm */)
            {
                // only write version on an empty DB
                if (m_height == 0)
                {
                    Dbt_copy<const char *> k("version");
                    Dbt_copy<uint32_t> v(VERSION);
                    auto put_result = m_properties->put(DB_DEFAULT_TX, &k, &v, 0);
                    if (put_result != 0)
                    {
                        m_open = false;
                        LOG_PRINT_RED_L0("Failed to write version to database.");
                        return;
                    }
                }
            }

            // run checkpoint thread
            m_run_checkpoint = true;
            m_checkpoint_thread.reset(new boost::thread(&BlockchainBDB::checkpoint_worker, this));
        }
        catch (const std::exception &e)
        {
            throw0(DB_OPEN_FAILURE(e.what()));
        }

        m_open = true;
    }

    void BlockchainBDB::close()
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        this->sync();

        m_run_checkpoint = false;
        m_checkpoint_thread->join();
        m_checkpoint_thread.reset();

        // FIXME: not yet thread safe!!!  Use with care.
        m_open = false;

        // DB_FORCESYNC is only available on newer version of libdb.
        // The libdb doc says using the DB_FORCESYNC flag to DB_ENV->close
        // is "similar to calling the DB->close(0) method to close each
        // database handle". So this is what we do here as a fallback.
#ifdef DB_FORCESYNC
        m_env->close(DB_FORCESYNC);
#else
        m_blocks->close(0);
        m_block_heights->close(0);
        m_block_hashes->close(0);
        m_block_timestamps->close(0);
        m_block_sizes->close(0);
        m_block_diffs->close(0);
        m_block_coins->close(0);

        m_txs->close(0);
        m_tx_unlocks->close(0);
        m_tx_heights->close(0);
        m_tx_outputs->close(0);

        m_output_txs->close(0);
        m_output_indices->close(0);
        m_output_amounts->close(0);
        m_output_keys->close(0);

        m_spent_keys->close(0);

        m_hf_starting_heights->close(0);
        m_hf_versions->close(0);

        m_properties->close(0);

        m_env->close(0);
#endif
    }

    void BlockchainBDB::sync()
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        try
        {
            m_blocks->sync(0);
            m_block_heights->sync(0);
            m_block_hashes->sync(0);
            m_block_timestamps->sync(0);
            m_block_sizes->sync(0);
            m_block_diffs->sync(0);
            m_block_coins->sync(0);

            m_txs->sync(0);
            m_tx_unlocks->sync(0);
            m_tx_heights->sync(0);
            m_tx_outputs->sync(0);

            m_output_txs->sync(0);
            m_output_indices->sync(0);
            m_output_amounts->sync(0);
            m_output_keys->sync(0);

            m_spent_keys->sync(0);

            if (m_hf_starting_heights != nullptr)
                m_hf_starting_heights->sync(0);
            if (m_hf_versions != nullptr)
                m_hf_versions->sync(0);

            m_properties->sync(0);
        }
        catch (const std::exception &e)
        {
            throw0(DB_ERROR(std::string("Failed to sync database: ").append(e.what()).c_str()));
        }
    }

    void BlockchainBDB::reset()
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        bdb_txn_safe txn;
        if (m_env->txn_begin(NULL, txn, 0))
            throw0(DB_ERROR("Failed to create a transaction for the db"));
        m_write_txn = &txn;
        try
        {
            uint32_t count;

            m_blocks->truncate(*m_write_txn, &count, 0);
            m_block_heights->truncate(*m_write_txn, &count, 0);
            m_block_hashes->truncate(*m_write_txn, &count, 0);
            m_block_timestamps->truncate(*m_write_txn, &count, 0);
            m_block_sizes->truncate(*m_write_txn, &count, 0);
            m_block_diffs->truncate(*m_write_txn, &count, 0);
            m_block_coins->truncate(*m_write_txn, &count, 0);

            m_txs->truncate(*m_write_txn, &count, 0);
            m_tx_unlocks->truncate(*m_write_txn, &count, 0);
            m_tx_heights->truncate(*m_write_txn, &count, 0);
            m_tx_outputs->truncate(*m_write_txn, &count, 0);

            m_output_txs->truncate(*m_write_txn, &count, 0);
            m_output_indices->truncate(*m_write_txn, &count, 0);
            m_output_amounts->truncate(*m_write_txn, &count, 0);
            m_output_keys->truncate(*m_write_txn, &count, 0);

            m_spent_keys->truncate(*m_write_txn, &count, 0);

            m_hf_starting_heights->truncate(*m_write_txn, &count, 0);
            m_hf_versions->truncate(*m_write_txn, &count, 0);

            m_properties->truncate(*m_write_txn, &count, 0);
        }
        catch (const std::exception &e)
        {
            throw0(DB_ERROR(std::string("Failed to reset database: ").append(e.what()).c_str()));
        }
        m_write_txn = NULL;
    }

    std::vector<std::string> BlockchainBDB::get_filenames() const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        std::vector<std::string> filenames;

        char *fname, *dbname;
        const char **pfname, **pdbname;

        pfname = (const char **)&fname;
        pdbname = (const char **)&dbname;

        m_blocks->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        m_block_heights->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        m_block_hashes->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        m_block_timestamps->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        m_block_sizes->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        m_block_diffs->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        m_block_coins->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        m_txs->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        m_tx_unlocks->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        m_tx_heights->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        m_tx_outputs->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        m_output_txs->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        m_output_indices->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        m_output_amounts->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        m_output_keys->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        m_spent_keys->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        m_hf_starting_heights->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        m_hf_versions->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        m_properties->get_dbname(pfname, pdbname);
        filenames.push_back(fname);

        std::vector<std::string> full_paths;

        for (auto &filename : filenames)
        {
            boost::filesystem::path p(m_folder);
            p /= filename;
            full_paths.push_back(p.string());
        }

        return full_paths;
    }

    bool BlockchainBDB::remove_data_file(const std::string &folder)
    {
        return true;
    }

    std::string BlockchainBDB::get_db_name() const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);

        return std::string("BerkeleyDB");
    }

    // TODO: this?
    bool BlockchainBDB::lock()
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();
        return false;
    }

    // TODO: this?
    void BlockchainBDB::unlock()
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();
    }

    bool BlockchainBDB::block_exists(const crypto::hash &h, uint64_t *height) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<crypto::hash> key(h);

        auto get_result = m_block_heights->exists(DB_DEFAULT_TX, &key, 0);
        if (get_result == DB_NOTFOUND)
        {
            LOG_PRINT_L3("Block with hash " << epee::string_tools::pod_to_hex(h) << " not found in db");
            return false;
        }
        else if (get_result)
            throw0(DB_ERROR("DB error attempting to fetch block index from hash"));

        if (height)
            *height = get_result - 1;

        return true;
    }

    block BlockchainBDB::get_block(const crypto::hash &h) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        return get_block_from_height(get_block_height(h));
    }

    uint64_t BlockchainBDB::get_block_height(const crypto::hash &h) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<crypto::hash> key(h);
        Dbt_copy<uint32_t> result;

        auto get_result = m_block_heights->get(DB_DEFAULT_TX, &key, &result, 0);
        if (get_result == DB_NOTFOUND)
            throw1(BLOCK_DNE("Attempted to retrieve non-existent block height"));
        else if (get_result)
            throw0(DB_ERROR("Error attempting to retrieve a block height from the db"));

        return result - 1;
    }

    block_header BlockchainBDB::get_block_header(const crypto::hash &h) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        // block_header object is automatically cast from block object
        return get_block(h);
    }

    block BlockchainBDB::get_block_from_height(const uint64_t &height) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<uint32_t> key(height + 1);
        Dbt_safe result;
        auto get_result = m_blocks->get(DB_DEFAULT_TX, &key, &result, 0);
        if (get_result == DB_NOTFOUND)
        {
            throw0(BLOCK_DNE(std::string("Attempt to get block from height ").append(boost::lexical_cast<std::string>(height)).append(" failed -- block not in db").c_str()));
        }
        else if (get_result)
            throw0(DB_ERROR("Error attempting to retrieve a block from the db"));

        blobdata bd;
        bd.assign(reinterpret_cast<char *>(result.get_data()), result.get_size());

        block b;
        if (!parse_and_validate_block_from_blob(bd, b))
            throw0(DB_ERROR("Failed to parse block from blob retrieved from the db"));

        return b;
    }

    uint64_t BlockchainBDB::get_block_timestamp(const uint64_t &height) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<uint32_t> key(height + 1);
        Dbt_copy<uint64_t> result;
        auto get_result = m_block_timestamps->get(DB_DEFAULT_TX, &key, &result, 0);
        if (get_result == DB_NOTFOUND)
        {
            throw0(BLOCK_DNE(std::string("Attempt to get timestamp from height ").append(boost::lexical_cast<std::string>(height)).append(" failed -- timestamp not in db").c_str()));
        }
        else if (get_result)
            throw0(DB_ERROR("Error attempting to retrieve a timestamp from the db"));

        return result;
    }

    uint64_t BlockchainBDB::get_top_block_timestamp() const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        // if no blocks, return 0
        if (m_height == 0)
        {
            return 0;
        }

        return get_block_timestamp(m_height - 1);
    }

    size_t BlockchainBDB::get_block_weight(const uint64_t &height) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<uint32_t> key(height + 1);
        Dbt_copy<size_t> result;
        auto get_result = m_block_sizes->get(DB_DEFAULT_TX, &key, &result, 0);
        if (get_result == DB_NOTFOUND)
        {
            throw0(BLOCK_DNE(std::string("Attempt to get block size from height ").append(boost::lexical_cast<std::string>(height)).append(" failed -- block size not in db").c_str()));
        }
        else if (get_result)
            throw0(DB_ERROR("Error attempting to retrieve a block size from the db"));

        return result;
    }

    difficulty_type BlockchainBDB::get_block_cumulative_difficulty(const uint64_t &height) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__ << "  height: " << height);
        check_open();

        Dbt_copy<uint32_t> key(height + 1);
        Dbt_copy<difficulty_type> result;
        auto get_result = m_block_diffs->get(DB_DEFAULT_TX, &key, &result, 0);
        if (get_result == DB_NOTFOUND)
        {
            throw0(BLOCK_DNE(std::string("Attempt to get cumulative difficulty from height ").append(boost::lexical_cast<std::string>(height)).append(" failed -- difficulty not in db").c_str()));
        }
        else if (get_result)
            throw0(DB_ERROR("Error attempting to retrieve a cumulative difficulty from the db"));

        return result;
    }

    difficulty_type BlockchainBDB::get_block_difficulty(const uint64_t &height) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        difficulty_type diff1 = 0;
        difficulty_type diff2 = 0;

        diff1 = get_block_cumulative_difficulty(height);
        if (height != 0)
        {
            diff2 = get_block_cumulative_difficulty(height - 1);
        }

        return diff1 - diff2;
    }

    uint64_t BlockchainBDB::get_block_already_generated_coins(const uint64_t &height) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<uint32_t> key(height + 1);
        Dbt_copy<uint64_t> result;
        auto get_result = m_block_coins->get(DB_DEFAULT_TX, &key, &result, 0);
        if (get_result == DB_NOTFOUND)
        {
            throw0(BLOCK_DNE(std::string("Attempt to get generated coins from height ").append(boost::lexical_cast<std::string>(height)).append(" failed -- block size not in db").c_str()));
        }
        else if (get_result)
            throw0(DB_ERROR("Error attempting to retrieve a total generated coins from the db"));

        return result;
    }

    crypto::hash BlockchainBDB::get_block_hash_from_height(const uint64_t &height) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<uint32_t> key(height + 1);
        Dbt_copy<crypto::hash> result;
        auto get_result = m_block_hashes->get(DB_DEFAULT_TX, &key, &result, 0);
        if (get_result == DB_NOTFOUND)
        {
            throw0(BLOCK_DNE(std::string("Attempt to get hash from height ").append(boost::lexical_cast<std::string>(height)).append(" failed -- hash not in db").c_str()));
        }
        else if (get_result)
            throw0(DB_ERROR("Error attempting to retrieve a block hash from the db."));

        return result;
    }

    std::vector<block> BlockchainBDB::get_blocks_range(const uint64_t &h1, const uint64_t &h2) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();
        std::vector<block> v;

        for (uint64_t height = h1; height <= h2; ++height)
        {
            v.push_back(get_block_from_height(height));
        }

        return v;
    }

    std::vector<crypto::hash> BlockchainBDB::get_hashes_range(const uint64_t &h1, const uint64_t &h2) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();
        std::vector<crypto::hash> v;

        for (uint64_t height = h1; height <= h2; ++height)
        {
            v.push_back(get_block_hash_from_height(height));
        }

        return v;
    }

    crypto::hash BlockchainBDB::top_block_hash() const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();
        if (m_height > 0)
        {
            return get_block_hash_from_height(m_height - 1);
        }

        return null_hash;
    }

    block BlockchainBDB::get_top_block() const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        if (m_height > 0)
        {
            return get_block_from_height(m_height - 1);
        }

        block b;
        return b;
    }

    uint64_t BlockchainBDB::height() const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        return m_height;
    }

    bool BlockchainBDB::tx_exists(const crypto::hash &h) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<crypto::hash> key(h);

        TIME_MEASURE_START(time1);
        auto get_result = m_txs->exists(DB_DEFAULT_TX, &key, 0);
        TIME_MEASURE_FINISH(time1);
        time_tx_exists += time1;
        if (get_result == DB_NOTFOUND)
        {
            LOG_PRINT_L1("transaction with hash " << epee::string_tools::pod_to_hex(h) << " not found in db");
            return false;
        }
        else if (get_result)
            throw0(DB_ERROR("DB error attempting to fetch transaction from hash"));

        return true;
    }

    uint64_t BlockchainBDB::get_tx_unlock_time(const crypto::hash &h) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<crypto::hash> key(h);
        Dbt_copy<uint64_t> result;
        auto get_result = m_tx_unlocks->get(DB_DEFAULT_TX, &key, &result, 0);
        if (get_result == DB_NOTFOUND)
            throw1(TX_DNE(std::string("tx unlock time with hash ").append(epee::string_tools::pod_to_hex(h)).append(" not found in db").c_str()));
        else if (get_result)
            throw0(DB_ERROR("DB error attempting to fetch tx unlock time from hash"));

        return result;
    }

    transaction BlockchainBDB::get_tx(const crypto::hash &h) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<crypto::hash> key(h);
        Dbt_safe result;
        auto get_result = m_txs->get(DB_DEFAULT_TX, &key, &result, 0);
        if (get_result == DB_NOTFOUND)
            throw1(TX_DNE(std::string("tx with hash ").append(epee::string_tools::pod_to_hex(h)).append(" not found in db").c_str()));
        else if (get_result)
            throw0(DB_ERROR("DB error attempting to fetch tx from hash"));

        blobdata bd;
        bd.assign(reinterpret_cast<char *>(result.get_data()), result.get_size());

        transaction tx;
        if (!parse_and_validate_tx_from_blob(bd, tx))
            throw0(DB_ERROR("Failed to parse tx from blob retrieved from the db"));

        return tx;
    }

    uint64_t BlockchainBDB::get_tx_count() const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        DB_BTREE_STAT *stats;

        // DB_FAST_STAT can apparently cause an incorrect number of records
        // to be returned.  The flag should be set to 0 instead if this proves
        // to be the case.
        m_txs->stat(DB_DEFAULT_TX, &stats, DB_FAST_STAT);
        auto num_txs = stats->bt_nkeys;
        delete stats;

        return num_txs;
    }

    std::vector<transaction> BlockchainBDB::get_tx_list(const std::vector<crypto::hash> &hlist) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();
        std::vector<transaction> v;

        for (auto &h : hlist)
        {
            v.push_back(get_tx(h));
        }

        return v;
    }

    uint64_t BlockchainBDB::get_tx_block_height(const crypto::hash &h) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<crypto::hash> key(h);
        Dbt_copy<uint64_t> result;
        auto get_result = m_tx_heights->get(DB_DEFAULT_TX, &key, &result, 0);
        if (get_result == DB_NOTFOUND)
        {
            throw1(TX_DNE(std::string("tx height with hash ").append(epee::string_tools::pod_to_hex(h)).append(" not found in db").c_str()));
        }
        else if (get_result)
            throw0(DB_ERROR("DB error attempting to fetch tx height from hash"));

        return (uint64_t)result - 1;
    }

    uint64_t BlockchainBDB::get_num_outputs(const uint64_t &amount) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        bdb_cur cur(DB_DEFAULT_TX, m_output_amounts);

        Dbt_copy<uint64_t> k(amount);
        Dbt_copy<uint32_t> v;
        auto result = cur->get(&k, &v, DB_SET);
        if (result == DB_NOTFOUND)
        {
            return 0;
        }
        else if (result)
            throw0(DB_ERROR("DB error attempting to get number of outputs of an amount"));

        db_recno_t num_elems = 0;
        cur->count(&num_elems, 0);

        cur.close();

        return num_elems;
    }

    output_data_t BlockchainBDB::get_output_key(const uint64_t &global_index) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<uint32_t> k(global_index);
        Dbt_copy<output_data_t> v;
        auto get_result = m_output_keys->get(DB_DEFAULT_TX, &k, &v, 0);
        if (get_result == DB_NOTFOUND)
            throw1(OUTPUT_DNE("Attempting to get output pubkey by global index, but key does not exist"));
        else if (get_result)
            throw0(DB_ERROR("Error attempting to retrieve an output pubkey from the db"));

        return v;
    }

    output_data_t BlockchainBDB::get_output_key(const uint64_t &amount, const uint64_t &index) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        uint64_t glob_index = get_output_global_index(amount, index);
        return get_output_key(glob_index);
    }

    tx_out_index BlockchainBDB::get_output_tx_and_index(const uint64_t &amount, const uint64_t &index) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        std::vector<uint64_t> offsets;
        std::vector<tx_out_index> indices;
        offsets.push_back(index);
        get_output_tx_and_index(amount, offsets, indices);
        if (!indices.size())
            throw1(OUTPUT_DNE("Attempting to get an output index by amount and amount index, but amount not found"));

        return indices[0];
    }

    std::vector<uint64_t> BlockchainBDB::get_tx_amount_output_indices(const crypto::hash &h) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();
        std::vector<uint64_t> index_vec;
        std::vector<uint64_t> index_vec2;

        // get the transaction's global output indices first
        index_vec = get_tx_output_indices(h);
        // these are next used to obtain the amount output indices

        transaction tx = get_tx(h);

        uint64_t i = 0;
        uint64_t global_index;
        for (const auto &vout : tx.vout)
        {
            uint64_t amount = vout.amount;

            global_index = index_vec[i];

            bdb_cur cur(DB_DEFAULT_TX, m_output_amounts);

            Dbt_copy<uint64_t> k(amount);
            Dbt_copy<uint32_t> v;

            auto result = cur->get(&k, &v, DB_SET);
            if (result == DB_NOTFOUND)
                throw1(OUTPUT_DNE("Attempting to get an output index by amount and amount index, but amount not found"));
            else if (result)
                throw0(DB_ERROR("DB error attempting to get an output"));

            db_recno_t num_elems = 0;
            cur->count(&num_elems, 0);

            uint64_t amount_output_index = 0;
            uint64_t output_index = 0;
            bool found_index = false;
            for (uint64_t j = 0; j < num_elems; ++j)
            {
                output_index = v;
                if (output_index == global_index)
                {
                    amount_output_index = j;
                    found_index = true;
                    break;
                }
                cur->get(&k, &v, DB_NEXT_DUP);
            }
            if (found_index)
            {
                index_vec2.push_back(amount_output_index);
            }
            else
            {
                // not found
                cur.close();
                throw1(OUTPUT_DNE("specified output not found in db"));
            }

            cur.close();
            ++i;
        }

        return index_vec2;
    }

    tx_out_index BlockchainBDB::get_output_tx_and_index_from_global(const uint64_t &index) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<uint32_t> k(index);
        Dbt_copy<crypto::hash> v;

        auto get_result = m_output_txs->get(DB_DEFAULT_TX, &k, &v, 0);
        if (get_result == DB_NOTFOUND)
            throw1(OUTPUT_DNE("output with given index not in db"));
        else if (get_result)
            throw0(DB_ERROR("DB error attempting to fetch output tx hash"));

        crypto::hash tx_hash = v;

        Dbt_copy<uint64_t> result;
        get_result = m_output_indices->get(DB_DEFAULT_TX, &k, &result, 0);
        if (get_result == DB_NOTFOUND)
            throw1(OUTPUT_DNE("output with given index not in db"));
        else if (get_result)
            throw0(DB_ERROR("DB error attempting to fetch output tx index"));

        return tx_out_index(tx_hash, result);
    }

    bool BlockchainBDB::has_key_image(const crypto::key_image &img) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<crypto::key_image> val_key(img);
        if (m_spent_keys->exists(DB_DEFAULT_TX, &val_key, 0) == 0)
        {
            return true;
        }

        return false;
    }

    // Ostensibly BerkeleyDB has batch transaction support built-in,
    // so the following few functions will be NOP.

    bool BlockchainBDB::batch_start(uint64_t batch_num_blocks)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        return false;
    }

    void BlockchainBDB::batch_commit()
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
    }

    void BlockchainBDB::batch_stop()
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
    }

    void BlockchainBDB::batch_abort()
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
    }

    void BlockchainBDB::set_batch_transactions(bool batch_transactions)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        m_batch_transactions = batch_transactions;
        LOG_PRINT_L3("batch transactions " << (m_batch_transactions ? "enabled" : "disabled"));
    }

    void BlockchainBDB::block_txn_start(bool readonly)
    {
        // TODO
    }

    void BlockchainBDB::block_txn_stop()
    {
        // TODO
    }

    void BlockchainBDB::block_txn_abort()
    {
        // TODO
    }

    uint64_t BlockchainBDB::add_block(const block &blk, size_t block_weight, const difficulty_type &cumulative_difficulty, const uint64_t &coins_generated, const std::vector<transaction> &txs)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        bdb_txn_safe txn;
        if (m_env->txn_begin(NULL, txn, 0))
            throw0(DB_ERROR("Failed to create a transaction for the db"));
        m_write_txn = &txn;

        uint64_t num_outputs = m_num_outputs;
        try
        {
            BlockchainDB::add_block(blk, block_weight, cumulative_difficulty, coins_generated, txs);
            m_write_txn = NULL;

            TIME_MEASURE_START(time1);
            txn.commit();
            TIME_MEASURE_FINISH(time1);
            time_commit1 += time1;
        }
        catch (const std::exception &e)
        {
            m_num_outputs = num_outputs;
            m_write_txn = NULL;
            throw;
        }

        return ++m_height;
    }

    void BlockchainBDB::pop_block(block &blk, std::vector<transaction> &txs)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        bdb_txn_safe txn;
        if (m_env->txn_begin(NULL, txn, 0))
            throw0(DB_ERROR("Failed to create a transaction for the db"));
        m_write_txn = &txn;

        uint64_t num_outputs = m_num_outputs;
        try
        {
            BlockchainDB::pop_block(blk, txs);

            m_write_txn = NULL;
            txn.commit();
        }
        catch (...)
        {
            m_num_outputs = num_outputs;
            m_write_txn = NULL;
            throw;
        }

        --m_height;
    }

    void BlockchainBDB::get_output_tx_and_index_from_global(const std::vector<uint64_t> &global_indices, std::vector<tx_out_index> &tx_out_indices) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();
        tx_out_indices.clear();

        for (const uint64_t &index : global_indices)
        {
            Dbt_copy<uint32_t> k(index);
            Dbt_copy<crypto::hash> v;

            auto get_result = m_output_txs->get(DB_DEFAULT_TX, &k, &v, 0);
            if (get_result == DB_NOTFOUND)
                throw1(OUTPUT_DNE("output with given index not in db"));
            else if (get_result)
                throw0(DB_ERROR("DB error attempting to fetch output tx hash"));

            crypto::hash tx_hash = v;

            Dbt_copy<uint64_t> result;
            get_result = m_output_indices->get(DB_DEFAULT_TX, &k, &result, 0);
            if (get_result == DB_NOTFOUND)
                throw1(OUTPUT_DNE("output with given index not in db"));
            else if (get_result)
                throw0(DB_ERROR("DB error attempting to fetch output tx index"));
            auto hashindex = tx_out_index(tx_hash, result);
            tx_out_indices.push_back(hashindex);
        }
    }

    void BlockchainBDB::get_output_global_indices(const uint64_t &amount, const std::vector<uint64_t> &offsets, std::vector<uint64_t> &global_indices)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        TIME_MEASURE_START(txx);
        check_open();

        bdb_cur cur(DB_DEFAULT_TX, m_output_amounts);
        uint64_t max = 0;
        for (const uint64_t &index : offsets)
        {
            if (index > max)
                max = index;
        }

        // get returned keypairs count
#define DB_COUNT_RECORDS(dbt, cnt)                                   \
    do                                                               \
    {                                                                \
        uint32_t *_p = (uint32_t *)((uint8_t *)(dbt)->data +         \
                                    (dbt)->ulen - sizeof(uint32_t)); \
        cnt = 0;                                                     \
        while (*_p != (uint32_t)-1)                                  \
        {                                                            \
            _p -= 2;                                                 \
            ++cnt;                                                   \
        }                                                            \
    } while (0);

        Dbt_copy<uint64_t> k(amount);
        Dbt_copy<uint32_t> v;
        uint64_t buflen = 0;
        uint64_t t_dbmul = 0;
        uint64_t t_dbscan = 0;

        auto result = cur->get(&k, &v, DB_SET);
        if (result == DB_NOTFOUND)
            throw1(OUTPUT_DNE("Attempting to get an output index by amount and amount index, but amount not found"));
        else if (result)
            throw0(DB_ERROR("DB error attempting to get an output"));

        db_recno_t num_elems = 0;
        cur->count(&num_elems, 0);

        if (max <= 1 && num_elems <= max)
            throw1(OUTPUT_DNE("Attempting to get an output index by amount and amount index, but output not found"));

        TIME_MEASURE_START(db2);
        if (max <= 1)
        {
            for (const uint64_t &index : offsets)
            {
                TIME_MEASURE_START(t_seek);

                auto result = cur->get(&k, &v, DB_SET);
                if (result == DB_NOTFOUND)
                    throw1(OUTPUT_DNE("Attempting to get an output index by amount and amount index, but amount not found"));
                else if (result)
                    throw0(DB_ERROR("DB error attempting to get an output"));

                for (uint64_t i = 0; i < index; ++i)
                    cur->get(&k, &v, DB_NEXT_DUP);

                uint64_t glob_index = v;

                LOG_PRINT_L3("L0->v: " << glob_index);
                global_indices.push_back(glob_index);

                TIME_MEASURE_FINISH(t_seek);
            }
        }
        else
        {
            // setup a 256KB minimum buffer size
            uint32_t pagesize = 256 * 1024;

            // Retrieve only a suitable portion of the kvp data, up to somewhere near
            // the maximum offset value being retrieved
            buflen = (max + 1) * 4 * sizeof(uint64_t);
            buflen = ((buflen / pagesize) + ((buflen % pagesize) > 0 ? 1 : 0)) * pagesize;

            bool nomem = false;
            Dbt data;

            bool singlebuff = buflen <= m_buffer.get_buffer_size();
            buflen = buflen < m_buffer.get_buffer_size() ? buflen : m_buffer.get_buffer_size();
            bdb_safe_buffer_t::type buffer = nullptr;
            bdb_safe_buffer_autolock<bdb_safe_buffer_t> lock(m_buffer, buffer);

            data.set_data(buffer);
            data.set_ulen(buflen);
            data.set_size(buflen);
            data.set_flags(DB_DBT_USERMEM);

            uint32_t curcount = 0;
            uint32_t blockstart = 0;
            for (const uint64_t &index : offsets)
            {
                if (index >= num_elems)
                {
                    LOG_PRINT_L1("Index: " << index << " Elems: " << num_elems << " partial results found for get_output_tx_and_index");
                    break;
                }

                // fixme! for whatever reason, the first call to DB_MULTIPLE | DB_SET does not
                // retrieve the first value.
                if (index <= 1 || nomem)
                {
                    auto result = cur->get(&k, &v, DB_SET);
                    if (result == DB_NOTFOUND)
                    {
                        throw1(OUTPUT_DNE("Attempting to get an output index by amount and amount index, but amount not found"));
                    }
                    else if (result)
                    {
                        throw0(DB_ERROR("DB error attempting to get an output"));
                    }

                    for (uint64_t i = 0; i < index; ++i)
                        cur->get(&k, &v, DB_NEXT_DUP);
                }
                else
                {
                    while (index >= curcount)
                    {
                        TIME_MEASURE_START(t_db1);
                        try
                        {
                            cur->get(&k, &data, DB_MULTIPLE | (curcount == 0 ? DB_SET : DB_NEXT_DUP));
                            blockstart = curcount;

                            int count = 0;
                            DB_COUNT_RECORDS((DBT *)&data, count);
                            curcount += count;
                        }
                        catch (const std::exception &e)
                        {
                            cur.close();
                            throw0(DB_ERROR(std::string("Failed on DB_MULTIPLE: ").append(e.what()).c_str()));
                        }

                        TIME_MEASURE_FINISH(t_db1);
                        t_dbmul += t_db1;
                        if (singlebuff)
                            break;
                    }

                    LOG_PRINT_L3("Records returned: " << curcount << " Index: " << index);
                    TIME_MEASURE_START(t_db2);
                    DBT *pdata = (DBT *)&data;

                    uint8_t *value;
                    uint64_t dlen = 0;

                    void *pbase = ((uint8_t *)(pdata->data)) + pdata->ulen - sizeof(uint32_t);
                    uint32_t *p = (uint32_t *)pbase;
                    if (*p == (uint32_t)-1)
                    {
                        value = NULL;
                    }
                    else
                    {
                        p -= (index - blockstart) * 2; // index * 4 + 2; <- if DB_MULTIPLE_KEY
                        value = (uint8_t *)pdata->data + *p--;
                        dlen = *p--;
                        if (value == (uint8_t *)pdata->data)
                            value = NULL;
                    }

                    if (value != NULL)
                    {
                        v = dlen == sizeof(uint64_t) ? *((uint64_t *)value) : *((uint32_t *)value);
                    }
                    TIME_MEASURE_FINISH(t_db2);
                    t_dbscan += t_db2;
                }

                uint64_t glob_index = v;

                LOG_PRINT_L3("L1->v: " << glob_index);
                global_indices.push_back(glob_index);
            }
        }
        TIME_MEASURE_FINISH(db2);

        cur.close();

        TIME_MEASURE_FINISH(txx);

        LOG_PRINT_L3("blen: " << buflen << " txx: " << txx << " db1: " << t_dbmul << " db2: " << t_dbscan);
    }

    void BlockchainBDB::get_output_key(const uint64_t &amount, const std::vector<uint64_t> &offsets, std::vector<output_data_t> &outputs) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();
        TIME_MEASURE_START(txx);
        outputs.clear();

        std::vector<uint64_t> global_indices;
        get_output_global_indices(amount, offsets, global_indices);

        TIME_MEASURE_START(db3);
        if (global_indices.size() > 0)
        {
            for (const uint64_t &index : global_indices)
            {
                Dbt_copy<uint32_t> k(index);
                Dbt_copy<output_data_t> v;

                auto get_result = m_output_keys->get(DB_DEFAULT_TX, &k, &v, 0);
                if (get_result == DB_NOTFOUND)
                    throw1(OUTPUT_DNE("output with given index not in db"));
                else if (get_result)
                    throw0(DB_ERROR("DB error attempting to fetch output tx hash"));

                output_data_t data = *(output_data_t *)v.get_data();
                outputs.push_back(data);
            }
        }

        TIME_MEASURE_FINISH(txx);
        LOG_PRINT_L3("db3: " << db3);
    }

    void BlockchainBDB::get_output_tx_and_index(const uint64_t &amount, const std::vector<uint64_t> &offsets, std::vector<tx_out_index> &indices)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        std::vector<uint64_t> global_indices;
        get_output_global_indices(amount, offsets, global_indices);

        TIME_MEASURE_START(db3);
        if (global_indices.size() > 0)
            get_output_tx_and_index_from_global(global_indices, indices);
        TIME_MEASURE_FINISH(db3);

        LOG_PRINT_L3("db3: " << db3);
    }

    std::map<uint64_t, uint64_t>::BlockchainBDB::get_output_histogram(const std::vector<uint64_t> &amounts) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        throw1(DB_ERROR("Not implemented."));
    }

    void BlockchainBDB::check_hard_fork_info()
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        if (m_hf_versions == nullptr)
        {
            LOG_PRINT_L0("hf versions DB not open, so not checking");
            return;
        }

        DB_BTREE_STAT *db_stat1, *db_stat2;

        // DB_FAST_STAT can apparently cause an incorrect number of records
        // to be returned.  The flag should be set to 0 instead if this proves
        // to be the case.

        // Set txn to NULL and DB_FAST_STAT to zero (0) for reliability.
        m_blocks->stat(NULL, &db_stat1, 0);
        m_hf_versions->stat(NULL, &db_stat2, 0);
        if (db_stat1->bt_nkeys != db_stat2->bt_nkeys)
        {
            LOG_PRINT_L0("num blocks " << db_stat1->bt_nkeys << " != "
                                       << "num hf_versions " << db_stat2->bt_nkeys << " - will clear the two hard fork DBs");

            bdb_txn_safe txn;
            bdb_txn_safe *txn_ptr = &txn;
            if (m_write_txn)
                txn_ptr = m_write_txn;
            else
            {
                if (m_env->txn_begin(NULL, txn, 0))
                    throw0(DB_ERROR("Failed to create a transaction for the db"));
            }

            try
            {
                uint32_t count;
                m_hf_starting_heights->truncate(*txn_ptr, &count, 0);
                LOG_PRINT_L0("hf_starting_heights count: " << count);
                m_hf_versions->truncate(*txn_ptr, &count, 0);
                LOG_PRINT_L0("hf_versions count: " << count);

                if (!m_write_txn)
                    txn.commit();
            }
            catch (const std::exception &e)
            {
                throw0(DB_ERROR(std::string("Failed to clear two hard fork DBs: ").append(e.what()).c_str()));
            }
        }
        delete db_stat1;
        delete db_stat2;
    }

    void BlockchainBDB::drop_hard_fork_info()
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        bdb_txn_safe txn;
        bdb_txn_safe *txn_ptr = &txn;
        if (m_write_txn)
            txn_ptr = m_write_txn;
        else
        {
            if (m_env->txn_begin(NULL, txn, 0))
                throw0(DB_ERROR("Failed to create a transaction for the db"));
        }

        try
        {
            m_hf_starting_heights->close(0);
            m_hf_versions->close(0);
            m_hf_starting_heights = nullptr;
            m_hf_versions = nullptr;
            if (m_env->dbremove(*txn_ptr, BDB_HF_STARTING_HEIGHTS, NULL, 0) != 0)
                LOG_ERROR("Error removing hf_starting_heights");
            if (m_env->dbremove(*txn_ptr, BDB_HF_VERSIONS, NULL, 0) != 0)
                LOG_ERROR("Error removing hf_versions");

            if (!m_write_txn)
                txn.commit();
        }
        catch (const std::exception &e)
        {
            throw0(DB_ERROR(std::string("Failed to drop hard fork info: ").append(e.what()).c_str()));
        }
    }

    void BlockchainBDB::set_hard_fork_version(uint64_t height, uint8_t version)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<uint32_t> val_key(height + 1);
        Dbt_copy<uint8_t> val(version);
        if (m_hf_versions->put(DB_DEFAULT_TX, &val_key, &val, 0))
            throw1(DB_ERROR("Error adding hard fork version to db transaction."));
    }

    uint8_t BlockchainBDB::get_hard_fork_version(uint64_t height) const
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        check_open();

        Dbt_copy<uint32_t> key(height + 1);
        Dbt_copy<uint8_t> result;

        auto get_result = m_hf_versions->get(DB_DEFAULT_TX, &key, &result, 0);
        if (get_result == DB_NOTFOUND || get_result == DB_KEYEMPTY)
            throw0(OUTPUT_DNE("Error attempting to retrieve hard fork version from the db"));
        else if (get_result)
            throw0(DB_ERROR("Error attempting to retrieve hard fork version from the db"));

        return result;
    }

    void BlockchainBDB::checkpoint_worker() const
    {
        LOG_PRINT_L0("Entering BDB checkpoint thread.");
        int count = 0;
        while (m_run_checkpoint && m_open)
        {
            // sleep every second, so we don't delay exit condition m_run_checkpoint = false
            sleep(1);
            // checkpoint every 5 minutes
            if (count++ >= 300)
            {
                count = 0;
                if (m_env->txn_checkpoint(0, 0, 0) != 0)
                {
                    LOG_PRINT_L0("BDB txn_checkpoint failed.");
                    break;
                }
            }
        }
        LOG_PRINT_L0("Leaving BDB checkpoint thread.");
    }

    bool BlockchainBDB::is_read_only() const
    {
        return false;
    }

    void BlockchainBDB::fixup(fixup_context const context)
    {
        LOG_PRINT_L3("BlockchainBDB::" << __func__);
        // Always call parent as well
        BlockchainDB::fixup(context);
    }

    void BlockchainBDB::set_service_node_data(const std::string &data, bool long_term)
    {
    }

    bool BlockchainBDB::get_service_node_data(std::string &data, bool long_term)
    {
        return false;
    }

    void BlockchainBDB::clear_service_node_data()
    {
    }

} // namespace cryptonote
